1. Field of the Invention
The instant invention pertains to a method for assaying inorganic phosphorus and to a reagent for use therein.
2. Description of the Prior Art
The use of molybdate in the determination of inorganic phosphorus was first suggested by Woods et al (1). Woods et al found that under suitable conditions molybdates react with phosphates to form heteropoly compounds such as ammonium phosphomolybdate. These compounds absorb in the ultraviolet range or can be reduced, using any of a wide range of reducing agents under conditions which do not reduce the excess molybdate present, to form molybdenum blue which can be measured at wavelengths above 600 nm.
Until now, all methods for phosphorus determination on whole serum (i.e., serum which has not been deproteinized) have been performed by an end point technique (2-7). In the end point technique, an initial absorbance reading is first taken of the reagent alone, a sample to be assayed is then added to the reagent, and after equilibrium has been reached a second absorbance reading is taken. From this change in absorbance the phosphorus concentration is calculated.
With the advent of rate analyzers, attempts have been made to produce a rate method for phosphorus determinations. However, to date such attempts have not yielded a rate methodology. In fact, Daly et al (8) reported that "the possibility of an initial rate reaction was eliminated when it was discovered that serum protein had an accelerating effect on the reaction. This phenomena varied from serum to serum without affecting the final absorbance difference between the blank and the reaction product".
Accordingly, it would be very desirable to have a reagent capable of being employed in a rate determination of inorganic phosphorus in serum.